1. Field of the Invention
The present invention generally relates to a resonance tag and, more particularly, to a revival preventing resonance tag.
2. The Prior Arts
A conventional resonance tag is composed of a capacitor and a coil, and constituting a LC circuit. Generally, the resonance tags are attached to products at stores, libraries, etc., for preventing shoplifting. When the product passes through a detector, the resonance tag receives an electromagnetic wave from the detector, thereby causing the tag to resonate to reflect an electromagnetic wave with the same frequency. That allows detecting shoplifting.
When the product is purchased normally, the resonance function of the tag is inactivated by a tag inactivator installed for example on a register. Thus the resonance tag does not reflect electromagnetic wave, so that a product can pass the detector without alarm.
The resonance tag is inactivated by appling a high voltage generated when the resonance tag is given a pulse wave or Joule heat accompanied by the high voltage to a dielectric layer of the capacitor to cause the dielectric breakdown thereof, thereby short-circuiting the LC circuit. However, as bent several times, the tag may be reactivated with two electrode patterns of the capacitor being insulated from each other again. As a result, there will be some troubles, and the resonance tags with preventing reactivation are needed.